High-Pressure Processing of Food | Hacker News Reader

High-Pressure Processing of Food

slideshare.net

123 pointsHillaryBriss101 comments

Pasteurization is one of the great lifesavers of the modern age, akin to the initial use of fire to cook food. We in the west can afford to be obsessed with "fresh" because, thanks to modern scientific agriculture, we don't have to deal with so many pathogens. But the bugs are still out there. Cook your food properly. I would be extremely cautious about any new sterilization tech. I want it tested not just on clean food from clean farms, but on the horrible stuff not normally seen in our food chains.

I like my steak overcooked, cooked to the point of wrecking it, because where I grew up eating under-cooked meat was a serious health hazard. We used to wash our vegetables in water with a bit of bleach. Whenever I see someone eating a bloody steak, or vegetables rinsed only in tapwater, I shudder a little.

Does it kill pork tapeworms?

https://www.cbc.ca/radio/asithappens/as-it-happens-friday-ed...

"Some people get it by ingesting microscopic tapeworm eggs found in raw or undercooked pork, or unwashed fruits and vegetables from overseas. But Palma has never travelled outside the U.S."

I'm a westerner now living in Vietnam. I travel around the country quite a bit by motorbike. Through all of the most rural places. I'm currently in the far north having driven up from the south.

People in this country leave all of the bits of meat out in the sun with flies and what not all over it. I've seen cows, chickens and pigs slaughtered on the side of dusty dirty roads. They eat the whole animal... entrails and all.

Most cooking of meat just means it has been boiled in the bowl you're eating it out of. The concept of sanitization here is incomprehensible, it just does not exist. Literally, millions of people live like this... not even because they have to, there is actually a lot of money here... but because they just don't know any better.

Needless to say, I've become vegetarian with eggs. You just can't trust the meat at all. My diet on the road is the same almost every day... fried rice, tofu with tomato, fried eggs, boiled veggies. When I first moved here 3 years ago I would be sick a lot, but now my belly is used to it. Worst is a bit of belly ache.

Salad, home-made sauces, home-made lemonade, popsicles, etc. are the stuff that will really get you sick in rural places. (Assuming you aren’t eating raw river fish or something.) You can get all kinds of fun diseases from drinking untreated water or eating any food containing untreated water.

Boiled meat should be fine though. Becoming a hot-soup-a-tarian wouldn’t be the worst idea if getting sick is your big fear.

We descend from thousands of generations of people who ate meat without the benefit of refrigeration or USDA inspections. Unless you have other health problems already, the meat is fine. (I guess "mad cow disease" is an exception, but that's a really long-term exception.)

Yes I have lived in SE Asia. I never hesitated to eat at the restaurants next door to the meat markets that had never seen refrigeration.

All diseases originally came from someone else.

The fact there are 8 billion people in the world rather than 1 million is a big part of why you have to be so much more careful with food safety.

The chance that a random liter of river water contains pathogens from someone else is much higher now than a few hundred years ago.

> who ate meat without the benefit of refrigeration or USDA inspections

There is a reason why those exist and it's not for fun.

They also knew (a bit) how to keep it good (for a while) without refrigeration.

Hence beef jerky, ham curing and other techniques. It would also get cooked on the day if not processed. In northern Europe the weather also helps.

Not to mention the tapeworms and other nice stuff laying around.

Your SE restaurants probably deep fried the stuff or left it cooking for long.

YouTube Barnacle goosling. What you’ll see are small chicks jumping off a cliff and trying to fly with something like a 40-60% survival rate. Those chicks descended from thousands of generations that jumped off cliffs without the benefit of nets. That doesn’t mean that nets wouldn’t dramatically improve their survival rate!

This strikes me as an appeal to nature. So what if our ancestors survived without knowing better? We're all alive today despite horrific lack of food safety through the ages, not thanks to it. We have every reason to use modern, hard-earned scientific knowledge to ward off easily preventable diseases.

Boiled in the bowl you eat it from is pretty good sanitation IMO. Great if you can't count on anything to be clean, sterilize at the last step.

There's almost nothing that's unsafe well cooked unless it was rotten to begin with

Botulism. Pasteurization kills the bacteria, but it takes a ton of heat to kill the dangerous spores (250 F for three minutes).

The bacteria is aneorbic so it's not a huge danger outside of canned food

Isn't the gut moderately anaerobic?

It's the toxin the bacteria produces that's dangerous. AFAIK botulism bacteria don't grow inside humans

It can grow inside babies, which is why you can't feed babies honey.

You don't feed babies honey because they can choke on it.

That might be true, but the reason for this recommendation is because botulism spores can exist in honey and the systems (mostly gut bacteria, from what I understand) of infants are not developed enough to deal with it, unlike older children and adults.

AFAIK, spores have not been observed in US-sourced honey, but that is no guarantee.

I forgot about this, you're totally right

Prions

Prion diseases are a first-world problem where factory farms turn their cattle into cannibals.

> There's almost nothing that's unsafe well cooked unless it was rotten to begin with

Boiled rice - op's staple carbohydrate - can be dangerous if reheated. https://www.nhs.uk/common-health-questions/food-and-diet/can...

> Uncooked rice can contain spores of Bacillus cereus, a bacterium that can cause food poisoning. The spores can survive when rice is cooked.

> If rice is left standing at room temperature, the spores can grow into bacteria. These bacteria will multiply and may produce toxins (poisons) that cause vomiting or diarrhoea.

> The longer cooked rice is left at room temperature, the more likely it is that the bacteria or toxins could make the rice unsafe to eat.

> where I grew up eating under-cooked meat was a serious health hazard.

This is a not-so-obvious fact I only learned about in my 20s : that everyday food can be dangerous. I grew up in a very rural area and never thought our food couldn't be safe (except the milk, we had to boil it once back back from the farmer next door). I liked to eat bits of raw meat while my mother cooked and always thought we rinsed the vegetables only because they taste and look better without the dirt and small bugs.

Maybe I was lucky to live in a "safe food zone" (Europe, France). Is there any data on the prevalence of food pathogens? Also, is there any correlation between gut problems and being raised in rural vs. urban areas?

Modern farming practices really help. The cows/pigs are kept far away, and downhill, of the fields growing vegetables. Irrigation water isn't contaminated. Humans are in minimal contact with the crop. Like it or not, epic agribusiness dramatically reduces the risk of cross-contamination between crops/livestocks/peoples.

> I liked to eat bits of raw meat while my mother cooked and always thought we rinsed the vegetables only because they taste and look better without the dirt and small bugs.

With healthy livestock the chances of getting anything from eating raw meat are very low. With healthy livestock is a pretty big caveat though. Most people throughout history have had parasites, never mind animals. Industrial agriculture has the benefit of antibiotics and other medicines so most livestock is healthy. My biology lecturer in college said he wouldn’t eat fish, poultry or pig raw, everything else was basically ok. Fish because wild fish are crawling with parasites, poultry because salmonella is everywhere and pigs because of ringworm.

Vegetables are safe if they haven’t had unfermented on them recently but taking the time to let manure rot doesn’t always happen in places where that’s the only fertiliser you’ve got. If you can buy nitrogenous fertiliser by the bag you’re overwhelmingly going to be fine but generally safe food is not natural, it’s the product of work.

In France, toxoplasmosis is very commonly acquired from food.

In 1965, 83% of pregnant women in France were found to have it. This dropped to 37% by 2010.

Infection normally causes subtle behavior changes. There may be more risk-taking behavior, leading to more car crashes and more promiscuity. Schizophrenia becomes more common.

So maybe you are affected, but you haven't noticed. Maybe you would have made different life choices without an infection. Maybe you would have avoided some injuries.

I've never heard of home paseurizing farm milk, is that common?

Yes. And easy. Though I would imagine not as common a practice as it was in the past.

In India, we always boil milk irrespective of source. That's way hotter than pasteurization.

HPP is awesome: extends shelf life with minimal flavor/texture changes. Favorite HPP product: "fresh" coconut water esp Harmless Harvest.

(I founded 3 successful food distribution startups)

I was wondering why harmless harvest tastes so much better than other coconut water. It’s way too expensive for me to regularly buy but the flavor is so much better.

Alas their green bottle lids are near impossible to twist open.

That stuff is the best coconut water money can buy in North America.

Fascinating.

So why exactly is this not widespread now?

Is it too new, too costly, or does it diminish the taste/texture more than the slides indicate?

Or is it just not necessary, e.g. most people either eat their food before it goes bad, or forget about it for so long that this wouldn't make much a difference anyways?

I have a hard time believing that subjecting, say, a crisp green pepper to pressure high enough to disrupt all bacteria wouldn't noticeably alter the texture (perhaps similar to how freezing does)... or just as bad, make it implode and rupture. (Although I guess you could poke a small hole in produce with hollow interiors.)

The equipment is very expensive. The packaging of the items themselves can have a higher cost also. Many items don't really taste noticeably different after a temperature-based pasteurization so for those, the increased cost isn't worth it.

Pasteurization is necessary for most packaged food products to be licensed for sale.

The big apps for this right now seem to be juice products. A heat-pasteurized juice is noticeably inferior to an HPP one.

You would typically not pasteurize an unpackaged product. You don't have to pasteurize a bell pepper.

It's not that rare now. I have seen some mainstream dairies using it for particular products distributed in EU. And many veggie smoothie brands use it in the UK. E.g. Savse.

I would like to see studies comparing it to pasteurization as I said in another comment. I believe pasteurization creates some denatured proteins and weird peptides due to heat shock that might not be very healthy. It'd be interesting to see whether HPP is better in this regard.

I'm no expert, but it seems like it would have to be better, no?

Pressure at these levels could damage cell walls but not break apart molecules the way heat does, right?

That's the claim, and I tend to believe it's true. But I'd like to see some convincing data.

It’s been widely used in the soft drinks and dairy sector for at least 5 years now. I was involved in a UK-based “cold pressed” juice business and we used HPP to extend shelf life of our drinks from 2-3 days to 20-25 days (depending on the ingredients). This was 2013-2015 and there were already facilities who would batch HPP products for companies like ours.

The CAPEX is expensive and it's a batch process. If you can scrounge up enough capital to overcome that hurdle though, the products are usually an instant hit locally.

We in the developing markets are usually stuck with recombined juices and UHT milk, so we get easily blown-away by how better these things taste.

The effects of (very) high pressure on life are relevant to SETI, since it probably rules out the existence of life deep in large water worlds, and in "ice giants" like Uranus and Neptune.

At very high pressure, it becomes energetically favorable for proteins to be broken down into individual amino acids. This is because amino acids are zwitterions, with a positive and negative charged ends. These charged parts pull in water molecules, which makes the Gibbs free energy of the reaction more favorable for solvolysis as pressure goes up.

Noticed the same thing with pressure cookers. Food that has been nuked with one will stay good at room temp for a surprising amount of time assuming no additional exposure to contamination

The point of a pressure cooker is to allow higher temperatures than 100°C, which cooks things faster. But anything higher than 60°C should kill almost all bacteria (possible exception: rice bacterial spores) if you cook it long enough. Have you done a side-by-side comparison of food cooked in a pressure cooker vs cooked at normal pressure?

Killing spores is a lot harder. They can sit around in harsh conditions for a few hundred years until the conditions are right to germinate. And cooked foods devoid of other life (competition!) is a perfect situation.

There’s a lot floating through the air, not just what comes on rice.

For immediate consumption, it’s not usually necessary to kill them, but for storage it can be.

It won't stay a spore when wet though. The difficulty is when dry, but in cooked food it's not going to stay in spore form.

That's why steam is used in medical sterilization, rather than just dry heat.

Pressure cookers have a much lower pressure (~2atm) than what's happening here

Our grandmothers canned countless jars of summer fruit and vegetables this way.

And occasionally got a case of botulism as an aside. Be careful when canning your own food, especially if you haven't done it before.

2030: year of 1930

I even find that leftovers from meals I've cooked in a pressure cooker last quite a long time in the fridge.

I'm a fan of irradiating food, but has never quite taken off.

Read through it all the way to see what it would do to beef, it looks like the meat will lose its color.

At HPBB last year (coincidentally in Japan where high pressure food sterilization was first commercialized) there was a whole series on high pressure sterilization of food.

The last presentation was a company with a scalable automated canning and sterilizing machine that was simply beautiful from an engineering standpoint.

Since we don't fully understand nutrients and how stuff like high pressure sterilization, heating, and other methods affect bioavailability, impact protein structure, and create other changes, it's all down to trying and learning as we go.

What's great about pressure is that it can deactivate and destroy some of the harmful organisms in food, but my curious concern is what does that do to the cellular material we want intact for our body, how does that affect the protein structure (for those not familiar, protein structure and folding is absolutely crucial for functionality).

Irradiation concerns me more than pressure because if you're not careful, you could be breaking bonds that you don't want to be breaking.

All in all it's a fascinating topic and important to everyone who eats.

You digestive system doesn't absorb intact protein but disintegrates it.

Look up variant Creutzfeldt-Jakob disease (aka Mad Cow Disease).

Largely caused by animals being fed their own kind, but once the protein is created, it's nearly impossible to destroy. It's denaturing temperature is 600+ degrees and it laughs in the face of irradiation. Id be curious if the prion is susceptible to high pressure treatment

What about microwave assisted sterlization, or similarly , micvac.com(a in package cooking where a valve released all air, and than created negative pressure to make the package vacuum sealed) ?

Why aren't they more common in ready meals ?

Pressures so high they aren't found in nature create all kinds of denatured proteins our digestive systems have never seen before. Most I'm sure won't do much, but some might turn out to harm us in unseen ways.

Is nobody just a little worried about consuming all those without some more serious safety tests first?

No. proteins are denatured by cooking and the digestive process, before being broken into constituent amino acids. It is both extremely unlikely that applying pressure would create either novelly denatured proteins or that said proteins, if formed, would be harmful.

The scenario isn't strictly impossible, but something reminiscent of an fda phase 1 study to ascertain safety of every food item to undergo the procedure is an insane standard[1]. Also a standard massively above and beyond anything our current food supply has ever had in place.

[1] Read: costs of study far outweigh benefits weighted by likelihood and severity of issue.

It’s extremely common—I visited an HPP facility and all kinds of food from deli meat to fresh juice were being processed. The same can be said for heat treating (i.e. cooking).

That said, I agree that food processing isn’t completely charted territory.

It'd be nice to compare the effects of HPP vs Pasteurization in milk, and whether it less disruptive.

Pasteurized milk doesn't ferment as well as raw milk, suggesting lots of peptides are altered. And that is why some cheese DOPs mandate raw milk (only on hard cheeses, as on soft ones it'd not be safe).

> only on hard cheeses, as on soft ones it'd not be safe

Actually that's not true. This is pretty much only a thing in the US. All across Europe you can get soft unpasteurized cheeses in any large supermarket with a good cheese selection. Stuff like Brie de Meaux, Reblochon, or the Belgian Herve, or even proper Camembert falls in this category.

Yes, but I meant softer than those and with much shorter fermentation times. You can't get unpasteurized mozzarella or feta. Or it must be really rare as I think it's gonna be really hard to meet pathogenic bacteria counts on every batch without astronomically expensive QC.

Yes, you can get unpasteurized mozzarella, it is really delicious. Look, in Europe you can buy a type of cheese called casu marzu - literally "rotten cheese" - where during fermentation, they cut a hole in the top and leave it outside, so that a special type of fly comes and lays eggs in the cheese. When these eggs hatch, the cheese becomes filled with larvae who crawl through the cheese and digest it, as part of the ripening process. When you buy it, it's still full of crawling larvae. My point is, in Europe we make a lot of really weird cheeses. Mostly people survive.

"Because of European Union food hygiene-health regulations, the cheese has been outlawed, and offenders face heavy fines"

https://en.wikipedia.org/wiki/Casu_marzu

Pasteurizing is an integral part of the cooking/preparation of some foods, they won't taste right without it.

The best example I have (since it's local to me) is Cocio chocolate milk. It has three ingredients: milk, cocoa and sugar. If you just mix those together in the right proportions, it does taste okay, but nowhere near what Cocio is supposed to taste like.

To get the right taste, the chocolate milk is boiled in the bottle for ~30 minutes, which caramelizes some of the sugars, and then it has to sit for around a week to mature.

I consider myself a bit of a chocolate milk aficionado, and in my opinion, no other chocolate milk comes even close to that taste and feel.

Fermentation is largely a product of naturally occurring bacteria is it not? Makes sense pasteurizing it and killing them all would prevent fermentation, which in this case would just be referred to as spoiling.

Absolutely, but if you add plenty of starters to pasteurized milk you can get nice fermentation. That's what most cheese producers do. Pasteurize and then ferment.

What I meant is that differences arising in fermentation processes of raw vs pasteurized milk may not be just due to the microbial populations present before adding more microbial starters. But also because pasteurization "damages" some proteins and lipids, which can't be subsequently processed by bacteria.

No, I think the point here is that even if you inoculate pasteurized milk with microbes, which you typically do in cheese- or yogurt-making to ensure that you grow the species you want, they still don’t grow as well nor produce the same end product.

When I make yogurt, I usually hold the milk at a high temperature (> 180F) for a while first — it improves the final texture. Raw is not necessarily better.

> Fresh or marinated meat: Iron in the myoglobin changes from ferrous to ferric and globin is denatured-the red color is lost.

For better or worse, it doesn't seem likely that the bioavailability is identical between ferrous and ferric iron. How significant are such changes? It'd be nice to see the results of some RCTs on rodents comparing this process to fresh and heat treated. I imagine high pressure would be nutritionally better or worse depending on the food.

Does anyone know if a 600 MPa pressure chamber, DIY or not, is within reach of a garden variety prepper?

For DIY, micvac.com is safe and may fit to the meal-prep community very well.

The basic idea is a single-use valve based plastic package that lets you cook the food in a microwave in a closed container with an open valve(for steam release), but once it starts cooling, the valve closes,all bacteria are dead, the steam inside the package than condenses , creating low-pressure inside the package, similar to vacuum packing.

They describe the tech in their site, and in their patents.

Diy for it seems tough, you have engineer the right valve and package to ensure that every food, in every microwave , will get sterilized by the heat.

Considering that the yield strength of a lot of steels is at or below 600 MPa I wonder what these machines are made out of. If you wanted to make one yourself a 50 ton hydraulic press would generate the pressure needed but the seals that you would need for this are crazy to be food safe.

Home canning would do almost the same effect for much cheaper.

> A typical HPP process uses food products packaged in a high-barrier, flexible pouch or a plastic container.

If the pressure medium doesn't enter the pouch maybe it doesn't need to be food safe.

The machinery is very expensive and DIYing something with those pressures is very dangerous, since you're building a bomb. That's about 2000x the pressure inside a champagne bottle and 20x the pressure of a bomb.

For reference the Max cylinder pressure in an ice vehicle is 20 MPa iirc

Diamond synthesis machines are at ~100 MPa. I wonder if these food ones are capable of making gems without high temperatures.

The high pressure high temperature synthesis (HPHT) use pressures from 5GPa and up, but as the slides talk about 600MPa as a useful pressure the difference is "only" a factor 10.

One additional issue with diamond synthesis with the HPHT is that you need 1400°C, and the correct mix of graphite and metallic catalysts.

Unfortunately the pressure in HPP machines is dispersed over a large vessel (foot scale diameter cylinders), while diamond anvil cells and the like focus that pressure at the mm/sub-mm scale.

Would be nice though!

Why would that matter? High pressure is high pressure. Large vessel would mean you can grow many diamonds at the same time, no?

You might be right... pressure needed for diamond synthesis is almost certainly much higher than for killing bacteria via pressure drop.

Turns out, it is, and they add temperature to the mix:

>They were able to heat carbon to about 3,000 °C (5,430 °F) under a pressure of 3.5 gigapascals (510,000 psi) for a few seconds.

Wouldn't the HPP process break the cell walls of the food being treated. This would lead to poor tasting and faster deteriorating of the food?

Freeze drying is a process for preserving food which shares the high pressure aspects of HPP. But apparently the pressure is not as high, and food can be stored for 20 years.

Freeze drying is largely about removing water. No water means no bacterial action. Instant mummification, in effect.

By the way, there's also Pulsed Electric Field Pasteurisation.

https://www.newfoodmagazine.com/article/2116/pulsed-electric...

The other day I was thinking about the survivability of microbes inside ice moons at various pressures and came across the the above topic.

It may well be that exomicrobes can be adapted to live at high pressures but not be able to surive at low pressures.

I am assuming this is the same thing as Cold Pressure processing seen by this hummus brand? http://www.bluemoose.com/about/

This site is unreadable on mobile. Does anyone have a link to a PDF version?

https://www.docdroid.net/file/download/1gE4Jhw/tdxsd5ty.pdf

Really? I had no problem on an iPhone X, swiped through the slides just fine. What platform are you on?

It worked fine on a 6" device on Firefox for Android for me, however the text was small, and when zooming it only shows the zoomed slides in the original viewpoint which doesn't change.

I tested on an iPhone 5S which has a much smaller screen, so I need to zoom, but when zooming the page ends up messed up.

Also on iPhone X. When zooming the layout becomes garbled and unreadable.

Does anyone have a sense for how much the machines cost?

Yes. I've looked into them for a project. They are very expensive. Like in the low 7 figures. They're high maintenance and the packaging for at least some foods required is relatively expensive too.

They're pretty much as this point only for large production facilities/copackers. They're useful basically for products where heat-based pasteurization has noticeable downsides.

We've been eating heat cooked food for millennia. We know it's more or less safe, and we have evolved suitable enzymes.

We've never eaten stuff which went through such a high pressure process. This is not your average pressure-cooker, look at the numbers.

We have no idea what eating this stuff does long term, just like micro-plastics for example.

Yet people here seem to be cheering and jumping head-first just because it's cool technology.

Even though we don't have long term experience the way we do with cooking, the description of the process on Wikipedia seems to suggest that it doesn't have much in the way of chemical effects on food. I'm definitely not an expert, and this is just an initial take, but I don't really see any mechanisms that could plausibly be dangerous.

In order to illustrate what I mean by a way that something could plausibly be dangerous: My understanding is that the molecules in most plastics contain chemicals that are known to be harmful. So even if we determine that it is not possible for them to break down into harmful chemicals in the body, it was plausible that they might.

Am I maybe missing some what that this process could be harmful?

The pressure may cause the container to release molecules into the food. Plastic that is normally considered food-safe might not be food-safe at these pressures.

They explicitly state that they don't really know how it affects proteins, only that they are changed in "complex" ways.

Here is one example of a protein change which is deadly: https://en.wikipedia.org/wiki/Prion

As far as I can tell it simply kills larger cells like bacteria and deactivates plant/fungus spores. It is not cooking the food.

I would not think it could do much, beyond maybe introducing more micro-plastics (the deck mentioned vacuum packaging food before being pressurized).

> We've been eating heat cooked food for millennia.

"We" have been eating raw food for millions of years, far longer than cooked foods, which are a relatively new phenomenon in our biochemical evolutionary history.

We can measure what it does. We can examine the inputs as well as the outputs.

Why are anti-science arguments from emotion/fear so common around new types of food technology? What is it about food specifically that triggers what appears to be a deep-seated fear of change in people?

Health has become a sort of religion for many. Health, food and religion frequently go together in old mythology and now new.

"Good for you" and "bad for you" spread like old myth, factions fight, people have incredibly strong beliefs sometimes which have at least a little basis in reality sometimes they are worse than harmless.

These days it just isn't because some mystical being said so.

The dimensionality of human health, nutrition, and environment over time is many orders of magnitude beyond a Python script. We know and (accurately) measure far far less than you think.

Except this presentation explicitly states that they don't really know what it does to proteins, only that the changes are "complex".

And you can turn your argument around. Why everytime "science" is involved, the immediate presumption is that it's safe, especially when it's done for profit and when we know you can pay to get whatever "science" you want. Remember the many studies funded by the food industry that showed that sugar is perfectly safe and that fat is the dangerous thing?

This is HN, where we worship textbook abstractions. Who are you question any of them?!

The only proper way to tell us that our abstractions leak is 20 years later, in an article in "The Atlantic", after the casualties are in!

Reply on news.ycombinator.com